Construction of spars and like members of aircraft



J. D. NORTH. CONSTRUCTION OF SPARS AND LIKE MEMBERS OF AIRCRAFT. APPLICATION FILED JUNE 28. I920.

1,360,67 1. P atented Nov. 30, 1920.

UNITED STATES SPFLATENTI OFFICE.

JOHN DUDLEY NORTH, OF BURGH 'AP'ION, ENGLAND, ASSIGNOR OF- ONE-HALF TO BOULTON & PAUL LIMITED, OF NORWICH, NORFOLK, ENGLAND.

CONSTRUCTION OF SPARS AND LIKE MEMBERS OF AIRCRAFT.

Specificaticn of Letters Patent. Patented NOV. 30, 1920.

Application filed June 28, 1920. Serial No. 392,256.

To all whom it may concern:

Be it known that I, JOHN Donner NORTH, a subject of the King of Great Britain, residing at Burgh Apton, Norfolk, England, have invented certain new anduseful Improvements in the Construction of Spars and like Members of Aircraft, of which the following is a specification.

In the construction of metal spars and like members for aircraft which must be light in weight and therefore are built up with the walls or parts usually of sheet metal, it has been found desirable to stiffen the structure by means of distancing members located between opposite walls of the structure and firmly connected to both of said walls. In view of the fact that such distancing members must be rigid in themselves, fixed'firmly to the opposite walls of the structure, and at the same time must add but very little to the total weight, obvious difficulties have occurred which it is the object of the present invention to overcome.

The present invention consists in providing distancing members each consisting of a length of metal tube generally of thin steel having an external annular flange at a short distance from each end; the opposite Walls of a structure such as a metal spar are formed with through circular apertures, a circular aperture in one wallbeing opposite a circular aperture in the opposite Wall, and the tubular distance piece is located between the opposertl walls so that the latter bear against the flanges of the tubular memher while the ends of the latter project through the apertures, and the projecting ends are then flanged or spun over. Thus the opposed walls are prevented buckling either inward or outward.

Constructions of the tubular members will be hereafter described.

Referring to the drawings Figure 1 is a perspective view of the tubular stifliener, Fig. 2 is a horizontal section of the stiffener, Fig. 3 is an end view of a portion of a spar showing two opposite walls, partly in section, with the tubular distance piece or stiffener in position, and Fig. 4: is a horizontal section of a stiffener of a slightly modified construction. I

With reference to the drawing and more particularly to Figs. 1 and 2, the stiffener is shown as composed of a length of cylindrical tube 1 formed with two flanges 2, 3,

one at a short distance from each end, the flanges 2, 3 being external.

The external annular flanges 2, 3 are preferably formed according to this invention by pressing operations, the tube 1 being bulged outward annularly a short distance from each end, and further pressure is then exerted until the sides of each annular bulge are pressed firmly together so as to form external flanges 2, 3 to the tube 1 a short distance from each end.

The stiffener shown at Fig. 4 is similar in design to that shown at Figs. 1 and 2 but is constructed from sheet metal rolled to form a tube with a butt joint 8, after which the flanges and 3 are formed externally, as before described.

In utilizing such a stiffener, and referring more particularly to Fig. 3, the projecting ends 4, 5 extending beyond the flanges 2, 3 are passed through holes in the opposite Walls 6, 7 of a structure, so that the walls abut against the flanges 2, 3 of the tube 1, and the ends 4, 5 of the tube 1 project beyond the walls 6, 7 and are then flanged outwardly or spun over.

What I claim as my invention and desire to secure by Letters Patent is 1. In distancing and stiffening the opposite walls ofmetal spars and like structures ofaircraft; the combination with two oppo site walls of such a structure as aforesaid located at a distance apart and each wall having a through aperture, the aperture in one wall being opposite the aperture in the opposed wall; of a distancing member comprising a thin-walled metal tube having an external annular flange at a short distance from each end said tube being located between said opposite walls of said structure the ends of said metal tube extending through said opposite through aperturesin said' walls of said structure so that said wallscontact with said flanges of said metal tube, said metal tube having its ends projecting beyond said walls of said structure, flanged outwardly to retain said walls of said structure in position. v

2. In distancing and stifi'ening the oppositewalls of metal spars and like structures of aircraft; the combination with two opposite walls of such a structure as aforesaid located ata distance apart and each wall having a through aperture, the aperture in I I l l one wall being opposite the aperture in the 7 said flanges ofsaid metal tube, said metal opposed Wall; of a distaneing member comprising a thin-Walled metal tube, an external annular flange at a short distance from each end of said tube formed in apiece therewith by bulging outward annularlyi vhand 1n thepresence of two Witnesses.

said metal tube near each end and then pressing the sides of each annular bulge to produce said external flanges, the ends of said metal tube extending through said opposite through apertures in said Walls of said structure so that said Walls Contact with ube having its endsprojecting beyond said walls of saidstrueture, flai' ged outwardly-t0 5 'retainsaid Walls of said structure in position.

Inwitness whereof I have hereunto set my JO N DUDLEY NORTH;

Witnesses ICHARD 7 HOLMES,

HOMOR. 

